Add better routes for secondary DNS

We'd been doing no-gateway hostroutes for dns servers on secondary nets, but on
some devices (multi-homed stingray) this is a problem.  Add gateway-ed hostroutes
instead so the BP can do it's nonstandard "magical" demultiplexing.

bug:5011392
Change-Id: Ia48f69c8ddf2a37cfb8f014f078f96bf601d2ddb

core/java/android/net/LinkProperties.java

@@ -58,8 +58,8 @@ public class LinkProperties implements Parcelable {
     private ProxyProperties mHttpProxy;
 
     public static class CompareResult<T> {
-        public ArrayList<T> removed = new ArrayList<T>();
-        public ArrayList<T> added = new ArrayList<T>();
+        public Collection<T> removed = new ArrayList<T>();
+        public Collection<T> added = new ArrayList<T>();
 
         @Override
         public String toString() {